Convert a rate limit across time units
Type your budget once (say 60/min) and see what it means per second, hour, day, month and year — plus the inter-request interval.
How the math works
We normalize the rate to requests-per-second and project it onto every other time unit. The interval is 1/rate.
- 01
Type the rate
Number + unit, e.g. 100 / minute.
Parsing accepts ISO 8601, RFC 3339, RFC 2822, and Unix epoch seconds/milliseconds. The Date constructor handles the rest with browser-engine consistency.
inISO 8601RFC 3339epochlivein · timestamprate · ISO100/min
loaded · ISO 8601zone · ready - 02
Normalize
Convert to req/sec by dividing by 60, 3600 or 86400.
All math runs in UTC internally to avoid DST landmines; presentation converts back to the user’s zone via
Intl.DateTimeFormat.calcUTC mathIntlDST-safelive/s · optionsnorm · live1.667 req/s
options applied · UTCDST-safe - 03
Project
Multiply for minute, hour, day, month, year.
Output respects the chosen timezone offset (
Zvs+05:30) and pads digits per ISO conventions so sorts stay chronological.scaleoffsetzone-awaresortablepadded× · computedunits · ready× 86400 → /day
computed · instantsortable - 04
Read interval
1/rate gives the minimum time between requests.
Copy writes via the Async Clipboard API; nothing pings a time server — the browser’s clock is the only oracle.
intervalclipboardno oracledeterministicclient-sideΔt · copied1/r · done600 ms
shipped · ready to shipsuccess
Time math without DST landmines
Always store UTC
Convert to local for display only. UTC storage avoids DST jumps and timezone drift in databases.
Watch leap seconds
POSIX time doesn’t count leap seconds; some systems do. Don’t use timestamps for sub-second precision across boundaries.
Prefer Temporal eventually
The Date API has many quirks. Temporal is shipping in modern engines and handles zones correctly.
Cron is timezone-tricky
Cron expressions run in the daemon’s local zone unless told otherwise. Pin a TZ explicitly for predictable runs.
ISO 8601 sorts naturally
YYYY-MM-DDTHH:mm:ss sorts correctly as a string. Don’t use US-style MM/DD/YYYY for anything machine-readable.
Beware Y2K38
Signed 32-bit Unix timestamps overflow in 2038. Use 64-bit storage end-to-end for long-lived systems.
When to compute rate limits
APIs, queues, billing.
API budget
Does 60 req/min cover 100k req/day? Now you know. Math runs in UTC under the hood to dodge DST jumps — local time is only for display. That means scheduling logic and date diffs survive March / November fall-back without the classic off-by-one-hour bug.
DST-safeQueue sizing
Decide how big a buffer you need at a given inflow. Browser clock is the only source — no external time server, no privacy leak, no rate limit. Pair with NTP-synced server time for high-accuracy use cases, but for human-scale work the browser clock is plenty.
UTC-correctThrottling
Pick a delay that matches a vendor's rate cap. ISO 8601 output sorts naturally as strings, perfect for filenames (report-2026-01-15.pdf) and log lines that need chronological ordering without parsing. Drop into S3 keys for free time-bucketing.
ISO-sortableCost models
Project monthly volume from per-second rate. Pairs cleanly with cron, scheduled tasks, and timestamped log analysis. The tool's output drops directly into APScheduler, Linux cron, or GitHub Actions schedule expressions without re-formatting.
spec-gradePerformance tests
Tune k6 / artillery ramp-up to known throughput. Output respects the chosen timezone offset (Z vs +05:30) so REST APIs and database TIMESTAMP WITH TIME ZONE columns round-trip cleanly. No ambiguity between "noon UTC" and "noon local".
zone-awareWebhook spec
Document calls-per-day for an integrations doc. Confirms the difference between epoch seconds (10 digits) and milliseconds (13 digits) before you commit code that mis-multiplies by 1000 — a classic bug in cross-language time handling.
epoch-accurateFrequently asked questions
Something missing?
Tell us what you need. We ship the top requests every two weeks.